Pfizer (PFE) and Alliance Foundation Trials said Thursday that results from a phase 3 trial of the drug Ibrance showed that adding it to standard-of-care therapies extended median progression-free survival by over 15 months in patients with metastatic breast cancer.

The study involved patients with hormone receptor-positive, human epidermal growth factor receptor 2-positive metastatic breast cancer, according to a joint statement.

It showed a median progression-free survival of 44.3 months for 261 patients treated with Ibrance in combination with anti-HER2 therapy and endocrine therapy, compared with a median PFS of 29.1 months for 257 patients treated with anti-HER2 therapy and endocrine therapy alone, Pfizer and AFT said.

Pfizer is providing funding support for the trial, which is sponsored by AFT and cancer research groups in the US, Germany, Italy, Spain, Australia, and New Zealand.